"""
Hongyu (Vicky) Ye 
03/13/2021
Section #03
Part#4: Addition Table

"""
        
hasLowest = False
while True:
    if not hasLowest:
         lowest = int(input("Lowest number: "))
         if lowest >= 0:
             hasLowest = True
         else:
             print("Lowest number must be 0 or greater")
    else:
        highest = int(input("Highest number: "))
        if highest > 0 and highest > lowest:
            break
        else:
            print("Highest number must be larger than lowest number!")

while True:
    identify = input("Would you like to identify Prime numbers in your table? (y/n): ")
    if identify == "y" or identify == "n":
        break
    else:
        print("Invalid command, try again")

print("+     " + lowest + "   " + lowest+1 + "")
